It said penalties were levied against local officials who failed "to take decisive action" when petitioners from their area sought legal redress in provincial capitals and Beijing.

"The result is that petitioners to Beijing are routinely intercepted, harassed, and detained by government officials and security forces from their home areas intent on ensuring that petitioners are not detected seeking legal redress in Beijing or other major cities," the report said.

The Chinese government until recently denied the existence of such detentions, but has started to acknowledge the practise exists.

In December 2011, Beijing's public security bureau launched a six-month crackdown on such facilities operated by private security firms.

"The city's security market is in complete chaos. Some companies have been operating outside the law," Zhang Bing, deputy head of Beijing's public security bureau, was quoted as saying then by the Global Times newspaper.